Peak Flow Meter: Using the Zone System

What is the zone system?

The zone system is an easy way to check if your child's
asthma is in good control, if your child needs to take
medicine, or if you need to get help right away. The peak
flow meter can be marked with three colored zones (green,
yellow, and red). The zones are different for each person
and are based on your child's personal best peak flow
reading. Your child's personal best is determined by
checking and recording the peak flow twice a day for 2 weeks
while your child is healthy. Your health care provider will
help you figure out the right number range for each
zone. Many peak flow meters come with a sticker to mark the
zones.

What do the zones mean?

The colored zones on the peak flow meter are modeled after
the traffic light.

Green means good control (80 to 100% of personal best
reading).

Yellow means caution (50% to 80% of personal best
reading)

Red means danger (less than 50% of personal best reading)

Green zone: When the reading is in the green zone, it means
your child's asthma is under control and your child is not
having asthma symptoms.

Your child should:

continue to take his preventive medicine as prescribed

continue with everyday activities (school, play, sports).

If your child has stayed in the green zone for at least 3
months, talk to your health care provider about possibly
reducing your child's medicines.

Yellow Zone: If the reading is in the yellow zone, it means
your child is probably having asthma symptoms or may soon be
having symptoms (asthma attack). Your child may be having
difficulty with normal activities or having symptoms at
night.

Your child should:

Take his quick-relief (rescue) medicine as prescribed.

Take note of anything that may have caused the asthma
to get worse (for example, forgetting to take medicine or
being exposed to cigarette smoke).

If your child is often in the yellow zone, it means his
asthma is not under good control. Talk to your health care
provider about adjusting your child's medicine.

Red Zone: If the reading is in the red zone, it means your
child's asthma is seriously out of control. He is probably
having serious asthma symptoms such as extreme shortness of
breath (even at rest), chest tightness, wheezing, and
trouble talking.

You should:

Give your child the quick-relief medicine as prescribed
by your health care provider. Check with your health
care provider about how long you should wait to seek help
if the quick-relief medicine does not return your child
to the yellow or green zones.

This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.